This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/JP00/01683 which has an International filing date of Mar. 17, 2000, which designated the United States of America and was not published in English.
The invention relates to a collision determination method and a passive safety device. More specifically, the invention relates to a collision determination method and a passive safety device, which are provided to protect an occupant from shocks by an air bag at the time of collision.
FIG. 1 is an arrangement configuration view, schematically showing the arranged position of acceleration detecting sensors used for the conventional air bag passive safety device of a car. In FIG. 1, reference numeral 100 denotes a car main body; 101 a first satellite sensor arranged in a predetermined position in an engine room on the right side in a traveling direction, and capable of detecting initial impact acceleration at the time of collision; 102 similarly a second satellite sensor arranged in a predetermined position in an engine room on the left side in a traveling direction, and capable of detecting initial impact acceleration at the time of collision; 103 a built-in vehicle right side sensor arranged, for example, on the right side of the vehicle, for detecting side collision from the right side in the travelling direction of the car; 104 a built-in vehicle left side sensor arranged, for example, on the left side of the vehicle, for detecting side collision from the left side in the travelling direction of the car; and 105 a car compartment sensor arranged in a front panel in a car compartment.
Next, an operation will be described.
In such a passive safety device using satellite sensors 101 and 102, when the vehicle undergoes a head-on collision, the satellite sensors 101 and 102, and the car compartment sensor.105 detect deceleration caused by the head-on collision. However, as shown in FIG. 2, the deceleration detected by the satellite sensors 101 and 102 immediately after the occurrence of a head-on collision exhibits a steeper change than that detected by the car compartment sensor 15. As a result, compared with a case where collision determination is made based on the deceleration detected by the car compartment sensor 105, collision determination based on the deceleration detected by the satellite sensors 101 and 102 can be executed faster.
As the conventional collision determination method and passive safety device are constructed in the foregoing manner, collision can be determined faster by attaching the satellite sensors 101 and 102 towards the front side. However, in the case of a collision where the satellite sensors 101 and 102 are crushed during the latter half of the collision as shown in FIG. 2, the reliability of data regarding the deceleration or the like detected by the satellite sensors 101 and 102 is not guaranteed. Thus, in a conventional device performing collision determination based on the data regarding the deceleration or the like detected by the satellite sensors 101 and 102, it is impossible to make accurate collision determination for a collision in which the satellite sensors are crushed in the latter half of the collision.
The present invention was made to solve the foregoing problems, and an object of the invention is to provide a collision determination method and a passive safety device capable of performing highly reliable collision determination even for a collision in which the satellite sensors are crushed in the latter half of the collision.
A collision determination method according to the invention comprises the steps of: presetting a first reference value T, the first reference value being a minimum value of, a physical quantity detected by a car compartment sensor within a range where destruction of sensor disposed in the crushable area could occur as a result of the shocks applied in the crushable area; and invalidating the sensor output detected in the crushable area, when a physical quantity of the sensor output detected in the safety area as a result of the shocks applied in the crushable area exceeds the first reference value.
With the above arrangement, collision determination can be executed promptly by the satellite sensors. When the shocks in the crushable area are so great that the satellite sensors are destroyed, the sensor output detected in the crushable area is invalidated, so that a determination is made as to whether the collision necessitates the operation of an air bag device, based on the sensor output detected in the safety area. Thus, erroneous determination caused by the destruction of the satellite sensors is prevented, making it possible to perform highly reliable collision determination with regard to the operation of the air bag device.
The collision determination method further includes the steps of: when the physical quantity of the sensor output detected in the safety area as a result of the shocks applied in the crushable area is smaller than the first reference value, comparing the sensor output detected in the crushable area with a second reference value preset as a criterion for determination of a need to operate the air bag device, under a condition that the physical quantity of the sensor output detected in the safety area has not exceeded the first reference value; and making a determination as to whether the collision necessitates an operation of the air bag device, based on a result of the comparison.
With the above arrangement, when a shock is applied which does not result in a collision of the sensor disposed in the crushable area, collision determination is made based on the sensor output of the sensor disposed in the crushable area. Thus, it is possible to perform highly reliable collision determination.
The collision determination method may further comprise the steps of: when the physical quantity of the sensor output detected in the safety area as a result of the shocks applied in the crushable area is smaller than the first reference value, comparing an integrated-value of the sensor output detected in the crushable area with a third reference value preset as a criterion for determination of a need to operate the air bag device, under a condition that the physical quantity of the sensor output detected in the safety area has not exceeded the first reference value; and making a determination as to whether the collision necessitates an operation of the air bag device, based on a result of the comparison.
With the above arrangement, when a shock is applied which does not result in a destruction of the sensor disposed in the destruction area in the crushable area, collision determination is made based on the integrated value of the sensor output of the sensor disposed in the crushable area. Thus, it is possible to perform stable and highly reliable collision determination.
The collision determination method may further comprise the step of: when the physical quantity of the sensor output detected in the safety area as a result of the shocks applied in the crushable area is smaller than the first reference value, making a determination as to whether the collision necessitates an operation of the air bag device based on an ON/OFF signal outputted when shocks necessitating an operation of the air bag device are applied in the crushable area, under a condition that the physical quantity of the sensor output detected in the safety area has not exceeded the first reference value.
With the above arrangement, when a shock is applied which does not result in a destruction of the sensor disposed in the collision area, collision determination is made based on a sensor output outputted as an ON/OFF signal from the sensor disposed in the crushable area. Thus, it is possible to perform highly reliable collision determination.
The collision determination method may further comprise the step of: making a determination as to whether the collision necessitates an operation of the air bag device, based on the sensor output resulting from the shocks detected in the crushable area, when the sensor disposed in the crushable area does not undergo a destruction even if the output of a sensor disposed in the safety area exceeds the first reference value in response to the shocks applied in the crushable area.
With the above arrangement, when shocks occur, in which the first reference value T is exceeded, but the destruction of the sensor in the crushable area is not confirmed, failure diagnosis is performed for the sensor of the crushable area. If no failures have occurred, collision determination is executed again by the sensor of the crushable area. Thus, it is possible to perform prompt and highly reliable collision determination.
A passive safety device according to the invention comprises: a first sensor disposed in a crushable area which is the first area to undergo a destruction as a result of a collision; a second sensor disposed in a safety area which undergoes shocks resulting from the collision later; and collision determination means presetting a first reference value, the first reference value indicating a physical quantity detected by a car compartment sensor within a range where destruction of a sensor disposed in the crushable area could occur as a result of the shocks applied in the crushable area, and invalidating a sensor output detected by the first sensor, when a physical quantity of a sensor output detected by the second sensor as a result of the shocks applied in the crushable area exceeds the first reference value.
With the above configuration, collision determination can be executed promptly based on the output of the first sensor. When a shock is applied in the crushable area and the first sensor undergoes a destruction, the sensor output detected by the first sensor can be invalidated. Thus, erroneous determination caused by the destruction of the satellite sensor is prevented, making it possible to perform highly reliable collision determination with regard to the operation of an air bag device.
According to the passive safety device of the invention, the collision determination means: compares, when the physical quantity of the sensor output detected by the second sensor as a result of the shocks applied in the crushable area is smaller than the first reference value, a value of the sensor output detected by the first sensor with a second reference value preset as a criterion for determination of a need to operate the air bag device, under a condition that the physical quantity of the sensor output detected by the second sensor has not exceeded the first reference value; and makes a determination as to whether the collision necessitates an operation of the air bag device, based on a result of the comparison.
With the above configuration, when a shock is applied but the first sensor does not undergo a destruction, collision determination is executed based on the sensor output of the first sensor disposed in the crushable area. Thus, it is possible to perform highly reliable collision determination.
According to the passive safety device of the invention, the collision determination means compares, when the physical quantity of the sensor output detected by the second sensor as a result of the shocks applied in the crushable area is smaller than the first reference value, an integrated value of the sensor output detected by the first sensor with a third reference value preset as a criterion for determination of a need to operate the air bag device, under a condition that the physical quantity of the sensor output detected by the second, sensor has not exceeded the first reference value; and makes a determination as to whether the collision necessitates an operation of the air bag device, based on a result of the comparison.
With the above configuration, when a shock is applied but the first sensor does not undergo a destruction, collision determination is executed based on the integrated value of the sensor output of the first sensor. Thus, it is possible to perform stable and highly reliable collision determination.
According to the passive safety device of the invention, the collision determination means: makes a determination, when the physical quantity of the sensor output detected by the second sensor as a result of the shocks applied in the crushable area, is smaller than the first reference value, as to whether the collision necessitates an operation of the air bag device based on an ON/OFF signal outputted when shocks necessitating an operation of the air bag device are applied in the crushable area, under a condition that the physical quantity of the sensor output detected by the second sensor has not exceeded the first reference value
With the above configuration, when a shock is applied but the first sensor does not undergo a destruction, collision determination is executed based on the sensor output outputted as an ON/OFF signal from the first sensor. Thus, it is possible to perform highly reliable collision determination.